1. Field of the Invention
The present invention relates to a computer system and related method for calibrating a digitizer, and more specifically, to a computer system and related method for calibrating a digitizer without utilizing calibration software.
2. Description of the Prior Art
As the semiconductor manufacturing process progresses, an integrated circuit (IC) can contain more transistors for more complicated logic operations, and the operating ability of computers increases accordingly. Additionally, control signal input is quite important for users. From keyboard, mouse to trackball, as electronic products become more and more compact in size, digitizers have become an important input device in the next generation as they combine keyboard, mouse and handwriting input abilities. Using a digitizer, users can easily control a cursor or input characters in the handwritten way. Moreover, a touch screen combining input (digitizer) and output (screen) will provide a convenient input system.
Please refer to FIG. 1 showing a block diagram of a conventional computer system 10. The computer system 10 includes a host computer 12, a screen 14 and a digitizer 16. The host computer 12 has a central processing unit (CPU) 18, a north bridge circuit 20, a south bridge circuit 22, a display drive circuit 24, a memory 26 and a hard disk drive (HDD) 28. The digitizer 16 has a touch panel 29 and a control circuit 30, and the HDD 28 stores program codes of digitizer calibration software 32 and operating system (OS) 34. The CPU 18 is used for controlling the operation of the computer system 10, the north bridge circuit 20 is used for assisting data transmission between the CPU 18 and high-speed peripherals (e.g. the display drive circuit 24 and the memory 26), and the south bridge circuit 22 is used for assisting data transmission between the north bridge circuit 20 and low-speed peripherals (e.g. the HDD 28 and the digitizer 16). The display drive circuit 24 (e.g. a VGA card) is used for outputting video signals according to display data in order to drive the screen 14 to display images. The memory 26 is a volatile storage, and the HDD 28 is a non-volatile storage. The digitizer 16 is used for inputting control signals (e.g. cursor signals and character signals). If the touch panel 29 is a type of electro-resistive one, the user can press the touch panel 29 to generate sensing signals (e.g. voltage levels) to the control circuit 30, and then the control circuit 30 converts the sensing signals into corresponding coordinate values and sends them back to the host computer 12. Similarly, if the touch panel 29 is a type of electromagnetic one, the user can also generate sensing signals to be sent to the control circuit 30 by using the touch panel 29.
As known in the industry, the digitizer 16 requires calibration in cooperation with the screen 14 in order to convert the sensing signals accurately into coordinate values. Therefore, digitizer calibration software 32 stored on the HDD 28 is activated by the OS 34 in the host computer 12, and loaded to the memory 26 via the south bridge circuit 22. After the CPU 18 executes the program code for the digitizer calibration software 32, the digitizer calibration software 32 will generate display data, which is transmitted to the display drive circuit 24 via the north bridge circuit 20. The display drive circuit 24 continuously drives the screen 14 to display a calibration chart according to the display data. Please refer to FIG. 2 showing a calibration chart 36 on the screen 14 shown in FIG. 1. In FIG. 2, the calibration chart 36 includes a plurality of test marks 38, and each test mark 38 corresponds to a specific coordinate value on the screen 14. For instance, if the resolution of the screen 14 is 1024*768, the test marks 38 are located at the four corners having coordinate values (0, 0), (0, 768), (1024, 0), (1024, 768) of the screen 14 as shown in FIG. 2. Subsequently, the user can trigger corresponding sensing signals using the touch panel 29 according to the test marks, and the control circuit 30 converts the sensing signals into corresponding coordinate values A, B, C, D. Finally, the control circuit 30 calibrates these coordinate values input into the host computer according to the deviation between the coordinate values A, B, C, D and the coordinate values (0, 0), (0, 768), (1024, 0), (1024, 768). Therefore, after calibration is finished, when the user triggers corresponding sensing signals via the touch panel 29, the control circuit 30 can transmit the coordinate values (0, 0), (0, 768), (1024, 0), (1024, 768) accurately to the host computer 12.
As described above, the conventional computer system 10 uses the digitizer calibration software 32 to control the display drive circuit 24 to drive the screen 14, in order to display the calibration chart 36 with the test marks 38 thereon. That is, before the calibration of digitizer 16, the user is required to install the digitizer calibration software 32 into the computer system 10. Since different OS 34 utilizes different application program interface (API) functions, a digitizer calibration software 32 compatible with a specific OS cannot be installed or applied under another OS. For example, the digitizer calibration software 32 compatible with Windows™ can not be applied under the OS of Macintosh™. Furthermore, inappropriate digitizer calibration software 32 may cause malfunction or unstability of the computer system 10. Therefore, problems remain when calibrating the digitizer 16 using software.